1. Field of the Invention
This invention relates to a process for the simultaneous identification of Interferon-.alpha. and Interferon-.beta. gene expression vehicles, and the probe employed in that identification process.
2. Description of the Prior Art
Three types of human interferon are known from the literature, namely leucocyte interferon (interferon-.alpha., abbreviated to IFN-.alpha.), fibroblast interferon interferon-.beta., abbreviated to IFN-.beta.) and immune interferon (interferon-.gamma., abbreviated to IFN-.gamma.) (see W. E. Stewart II, "The Interferon System," Springer-Verlag Vienna/New York, 2nd edition (1981)). Human leucocytes or human myelobastoid cells stimulated with a virus produce leucocyte interferon, human fibroblasts which are induced with a virus or a suitable nucleic acid produce fibroblast interferon and human T-lymphocytes which are induced with mitogen, e.g. concanavalin, produce immune interferon.
It is also known that human cells of the B-lymphocyte type, as represented, for example, by the cell strains NC-37, Namalwa, Akuba or RPMI 1788, produce leucocyte interferon and fibroblast interferon simultaneously when stimulated by a virus (see Journal of General Virology 38, 51-59 (1977)). The proportions of IFN-.alpha. and IFN-.beta. produced can be varied by the choice of induction conditions (see Journal of Interferon Research 2, in preparation (1982)). For example, the following proportions of IFN-.alpha. and IFN-.beta. are obtained from different cell strains induced with Sendai virus:
______________________________________ Percentage of interferon activity neutralized by specific antisera against Cell strain IFN-.alpha. IFN-.beta. IFN-.alpha. + IFN-.beta. ______________________________________ Namalwa 52 34 .gtoreq.98 NC-37 40 52 .gtoreq.97 Akuba 85 27 .gtoreq.98 RPMI 1788 68 29 .gtoreq.98 ______________________________________
Moreover, molecular cloning of IFN-.alpha. genes from leucocytes (see Nature 284, 316-320 (1980); Science 209, 1343-1347 (1980) and EP-Al No. 0.032.134) and from myelobastoid cells (see Nature 287 411-416 (1980), ibid 290, 20-26 (1981) and GB-A No. 2.079.291) gave the result that IFN-.alpha. is coded by a family of genes which consists of at least 10 distinguishable genes and this in turn means that the gene products of these DNA sequences do not constitute a single uniform protein; this means that IFN-.alpha. is a mixture of similar proteins. These sub-types are referred to in the literature as IFN-.alpha. 1,2,3 . . . (see Nature 287, 401-408 (1980) and Gene 15, 379-394 (1981)) or LeIFN A,B,C . . . (see Nature 290, 20-26 (1981)).
On the other hand, a uniform DNA sequence was found for IFN-.beta.; this means that only a single gene codes for fibroblast interferon (see Nature 285, 542-547 (1980)).
Although no cross-hybridization takes place between IFN-.alpha. genes and the IFN-.beta. gene, contrary to what happens within the IFN-.alpha. gene family, the sequences have about 45% homology (see Nature 285, 547-549 (1980)). The longest fragment of sequence is 13 nucleotides long. This tridecanucleotide is known from the literature (see Eur. J. Cell. Biol. 25, 8-9 (1981)). The IFN-.alpha. genes containing this tridecanucleotide are LeIFN B,C,D,F,G; only 12 of the 13 nucletides are present in LeIFN A and H (See Nature 290, 20-26 (1981)).